Powder filling device with redundant powder collection mechanism, and rotary compression molding machine

Abstract

Disclosed is a powdery material filling device with a redundant (i.e., excess or waste) powdery material recovering mechanism. The powdery material filling device may be used in a rotary compression molding machine. In certain aspects, the redundant powdery material recovering mechanism is capable of actively recovering and reusing a redundant (i.e., excess or waste) powdery material even upon production of multi-layer tablets.

The invention claimed is: 
     
       1. A powdery material filling device having an excess powdery material recovering mechanism in a rotary compression molding machine having a rotating die table provided with a plurality of dies, and upper punches and lower punches located above and below the dies respectively, wherein the dies are configured to be filled with powdery material and then the upper punches and the lower punches are configured to sequentially compress and mold the filled powdery material in the dies, while the dies, the upper punches, and the lower punches are rotated along with the rotating die table, the device comprising:
 a powdery material filling unit configured to fill the dies with powdery material; 
 an excess powdery material recovering unit positioned downstream of the powdery material filling unit, the excess powdery material recovering unit configured for separating and recovering, from a surface of the rotating die table, excess powdery material leaked out of the powdery material filling unit and the dies onto the rotating die table; 
 an excess powdery material conveying unit configured to convey excess powdery material recovered by the excess powdery material recovering unit quasi-continuously in a predetermined constant amount of conveyance per unit time, wherein the amount of conveyance per unit time can be regulated; 
 a new powdery molding material supplying unit configured to supply the powdery material filling device with new powdery molding material; 
 a pre-mixed powdery material reserving unit connected to the new powdery molding material supplying unit and the excess powdery material conveying unit, the pre-mixed powdery material reserving unit configured to temporarily reserve the new powdery molding material supplied from the new powdery molding material supplying unit and the excess powdery material conveyed by the excess powdery material conveying unit; and 
 a powdery material mixing unit configured for mixing and substantially homogenizing the new powdery molding material and the excess powdery material transferred from the pre-mixed powdery material reserving unit, wherein: 
 the powdery material filling unit is configured to fill the dies with the powdery material that is mixed and substantially homogenized in the powdery material mixing unit, the powdery material having a substantially constant ratio between the new powdery material and the excess powdery material. 
 
     
     
       2. The powdery material filling device provided with the excess powdery material recovering mechanism according to  claim 1 , wherein at least one of the excess powdery material recovering unit and the excess powdery material conveying unit has an overflown powdery material discharger configured to discharge an overflown excess powdery material from the device. 
     
     
       3. The powdery material filling device provided with the excess powdery material recovering mechanism according to  claim 1 , wherein the excess powdery material conveying unit is located outside the rotating die table. 
     
     
       4. The powdery material filling device provided with the excess powdery material recovering mechanism according to  claim 1 , wherein the excess powdery material conveying unit has a tube-like structure or a gutter-like structure. 
     
     
       5. The powdery material filling device provided with the excess powdery material recovering mechanism according to  claim 1 , wherein the excess powdery material conveying unit is a conveyer or a spiral conveying machine having a screw in a tube-like structure. 
     
     
       6. The powdery material filling device provided with the excess powdery material recovering mechanism according to  claim 1 , wherein the new powdery molding material supplying unit, the pre-mixed powdery material reserving unit, the powdery material mixing unit, and the powdery material filling unit are located in this order vertically from top to bottom in the powdery filling device. 
     
     
       7. The powdery material filling device provided with the excess powdery material recovering mechanism according to  claim 1 , wherein the powdery material mixing unit and the powdery material filling unit are configured integrally. 
     
     
       8. The powdery material filling device provided with the excess powdery material recovering mechanism according to  claim 1 , wherein the pre-mixed powdery material reserving unit and the powdery material mixing unit are configured integrally. 
     
     
       9. The powdery material filling device provided with the excess powdery material recovering mechanism according to  claim 1 , wherein the powdery material mixing unit has a rotary blade for agitating the powdery material. 
     
     
       10. The powdery material filling device provided with the excess powdery material recovering mechanism according to  claim 1 , wherein the powdery material filling unit has a rotary blade or a ladder-like stepped portion. 
     
     
       11. The powdery material filling device provided with the excess powdery material recovering mechanism according to  claim 1 , wherein the excess powdery material recovering unit is a scraper made of material having hardness less than that of the rotating die table. 
     
     
       12. The powdery material filling device provided with the excess powdery material recovering mechanism according to  claim 1 , wherein at least one of the pre-mixed powdery material reserving unit, the powdery material mixing unit, and the powdery material filling unit includes a powdery material level sensor for constantly controlling an amount of the new powdery molding material supplied from the new powdery molding material supplying unit. 
     
     
       13. The powdery material filling device provided with the excess powdery material recovering mechanism according to  claim 1 , wherein the amount of conveyance per unit time by the excess powdery material conveying unit is set in accordance with an amount of the excess powdery material recovered by the excess powdery material recovering unit.